I think 3rd edition is going to be your friend, there. The rules are comprehensive enough to cover nearly anything you can imagine, but not cumbersome enough to slow down the game (once you get the hang of them - it might be kinda slow at first).
Once again, 3rd will be your friend here. Only one of you really needs the books. The rest can use the SRD to look up the specific things they need to know.
Really, you could do it without the books, but I think it would be very difficult to learn without them.
Um..... lol.
4th isn't really that bad. It just requires something of a different paradigm than 3rd. The rules are all focused on combat, but that actual encourages roleplaying, from my experience, because the players don't feel constrained by rules when they are not fighting.